Etching apparatus

ABSTRACT

Embodiments described herein relate to apparatus for performing electron beam reactive plasma etching (EBRPE). In one embodiment, an apparatus for performing EBRPE processes includes an electrode formed from a material having a high secondary electron emission coefficient. In another embodiment, an electrode is movably disposed within a process volume of a process chamber and capable of being positioned at a non-parallel angle relative to a pedestal opposing the electrode. In another embodiment, a pedestal is movably disposed with a process volume of a process chamber and capable of being positioned at a non-parallel angle relative to an electrode opposing the pedestal. Electrons emitted from the electrode are accelerated toward a substrate disposed on the pedestal to induce etching of the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 16/441,579, filed Jun. 14, 2019, which claims benefit of U.S.provisional patent application Ser. No. 62/687,760, filed Jun. 20, 2018.Each of the aforementioned related patent applications is hereinincorporated by reference.

BACKGROUND Field

Embodiments of the present disclosure generally relate to apparatus foretching a substrate. More specifically, embodiments described hereinrelate to methods and apparatus for electron beam reactive plasmaetching.

Description of the Related Art

In the semiconductor manufacturing industry, various technologicaladvances have enabled production of increasingly complex devices atadvanced technology nodes. For example, device feature sizes have beenreduced to the nanometer scale and the geometric complexity of suchfeatures has grown increasingly complex. Etching processes used tofabricate such devices are often a limiting factor in furtherdevelopment of advanced devices.

Reactive ion etching (RIE) is a conventional etching technique whichutilizes ion bombardment to induce etching reactions on a substrate.With RIE it is possible to generate anisotropic etching profiles,however, certain ion energy thresholds are often necessary to inducedesired etching reactions and to control the etching profile. The ionenergy thresholds often reduce etch selectivity and may damage thestructure being etched.

Electron beams are another technology commonly used in the semiconductormanufacturing industry. Electrons beams, when utilized with suitableetching gas chemistries, can induce etching on a substrate. However,conventional electron beam etching apparatus typically emit an electronbeam with a cross section on the micrometer scale which is not practicalfor forming nanometer scale advanced devices. In addition, conventionalelectron beam technology is typically unsuitable for fabrication ofadvanced optical devices and the like which employ complex topographicalfeatures.

Thus, what is needed in the art are improved etching apparatus.

SUMMARY

In one embodiment, a substrate processing apparatus is provided. Theapparatus includes a chamber body defining a volume, a pedestal disposedin the volume, and a ceiling coupled to the chamber body opposite thepedestal. An electrode is disposed in the volume between the pedestaland the ceiling. At least one of the electrode or the pedestal ismovable to orient a surface of the electrode facing a surface of thepedestal in a non-parallel orientation.

In another embodiment, a substrate processing apparatus is provided. Theapparatus includes a chamber body defining a volume, a ceiling coupledto the chamber body, an electrode coupled to the ceiling, and a pedestaldisposed in the volume and having a surface facing a surface of theelectrode. An actuator is coupled to the pedestal and configured toposition a surface of the pedestal facing the surface of the electrodein a non-parallel orientation relative to the surface of the electrode.

In yet another embodiment, a substrate processing apparatus is provided.The apparatus includes a chamber body defining a volume, an electrodefor performing electron beam reactive plasma etching disposed in thevolume, and a pedestal coupled to a support shaft, the pedestal beingdisposed in the volume opposite the electrode. A conductive mesh isdisposed in the pedestal, a plurality of shafts is coupled to either theelectrode or the pedestal, and one or more ball screw actuators arecoupled to the shafts. A first gas injector is coupled to the chamberbody adjacent to the electrode and a second gas injector is coupled tothe chamber body adjacent to the pedestal.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofits scope, and may admit to other equally effective embodiments.

FIG. 1 schematically illustrates an electron beam reactive plasmaetching (EBRPE) apparatus according to an embodiment described herein.

FIG. 2 schematically illustrates an EBRPE apparatus according to anotherembodiment described herein.

FIG. 3 illustrates an actuator assembly of an EBRPE apparatus accordingto an embodiment described herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments described herein relate to apparatus for performing electronbeam reactive plasma etching (EBRPE). In one embodiment, an apparatusfor performing EBRPE processes includes an electrode formed from amaterial having a high secondary electron emission coefficient. Inanother embodiment, an electrode is movably disposed within a processvolume of a process chamber and capable of being positioned at anon-parallel angle relative to a major axis of a pedestal opposing theelectrode. In another embodiment, a pedestal is movably disposed with aprocess volume of a process chamber and capable of being positioned at anon-parallel angle relative to a major axis of an electrode opposing thepedestal. Electrons emitted from the electrode are accelerated toward asubstrate disposed on the pedestal to induce etching of the substrate.

FIG. 1 schematically illustrates an electron beam reactive plasmaetching (EBRPE) chamber 100. The chamber 100 has a chamber body 102which defines a process volume 101. In one embodiment, the chamber body102 has a substantially cylindrical shape. In other embodiments, thechamber body 102 has a polygonal shape, such as a cubic shape or thelike. The chamber body 102 is fabricated from a material suitable formaintaining a vacuum pressure environment therein, such as metallicmaterials, for example aluminum or stainless steel.

A ceiling 106 is coupled to the chamber body 102 and bounds one side ofthe process volume 101. In one embodiment, the ceiling 106 is formedfrom an electrically conductive material, such as the materials utilizedto fabricate the chamber body 102. An electrode 108 is coupled to theceiling 106 and disposed within the process volume 101. A plurality ofactuators 184, 186 couple the electrode 108 to the ceiling 106. In oneembodiment, the actuators 184, 186 are disposed within recesses formedon a surface 185 of the ceiling 106 which faces and is exposed to theprocess volume 101. The actuators 184, 186, which may be electrical,pneumatic, mechanical, and/or hydraulic in nature of actuation, arecoupled by shafts 188, 190, which extend from respective actuators 184,186, to the electrode 108. In one embodiment, the actuators 184, 186 arestepper motors.

In one embodiment, the shaft 188 is disposed between the actuator 184and the electrode 108 and movably couples the electrode 108 to theceiling 106. Similarly, the shaft 190 is disposed between the actuator186 and the electrode 108 and movably couples the electrode 108 to theceiling 106. The actuators 184, 186 separately and independently controlthe movement of the shafts 188, 190 to enable positioning of theelectrode 108 at various angles relative to the ceiling 106. Forexample, as illustrated in FIG. 1 , the shaft 188 extends farther thanthe shaft 190 from the ceiling 106 to orient the electrode 108 at anon-parallel (i.e., at an angle) relative to the ceiling 106 within theprocess volume 101. In one embodiment, the shafts 188, 190 are leadscrews or ball screws.

Each of the shafts 188, 190 is coupled to the electrode 108 by arespective joint 187, 189. For example, the shaft 188 is coupled to theelectrode by the joint 187 and the shaft 190 is coupled to the electrode108 by the joint 189. The joints 187, 189 are rotational type jointsthat allow the electrode 108 to move independently of the shafts 188,190. Examples of suitable joint types include ball and socket joints,pivot joints, hinge joints, saddle joints, universal joints, and thelike.

In one embodiment, the electrode 108 is formed from a process-compatiblematerial having a high secondary electron emission coefficient, such assilicon, carbon, silicon carbon materials, or silicon-oxide materials.Alternatively, the electrode 108 is formed from a metal oxide materialsuch as aluminum oxide, yttrium oxide, or zirconium oxide. A dielectricring 109, which is formed from an electrically insulating material, iscoupled to the chamber body 102 and surrounds the ceiling 106, thuselectrically isolating the ceiling 106 from the chamber body 102. Asillustrated, the dielectric ring 109 is disposed between the chamberbody 102 and the ceiling 106 and supports the electrode 108 whichextends from the ceiling 106. In one embodiment, the dielectric ring 109is optional if the electrode 108 is otherwise electrically isolated fromthe chamber body 102.

A pedestal 110 is disposed in the process volume 101 below the electrode108. The pedestal 110 supports a substrate 111 thereon during processingand has a substrate support surface 110 a oriented parallel to theceiling 106. In one embodiment, the pedestal 110 is movable in the axialdirection by a lift servo 112. The lift servo 112 may optionally rotatethe pedestal 110. During operation, the substrate support surface 110 ais maintained at a distance of between about 1 inch and about 15 inchesfrom the electrode 108. In one embodiment, the pedestal 110 includes anelectrostatic chuck (ESC) 142 which forms the substrate support surface110 a. A conductive mesh 144 is disposed inside the ESC 142, and coupledto a chucking voltage supply 148. Power supplied to the mesh 144generates an electrostatic force that chucks the substrate 111 to thesurface 110 a. Additionally, a base layer 146 underlying the ESC 142 hasinternal passages 149 for circulating a thermal transfer medium (e.g., agas and/or a liquid) from a circulation supply 145. In one embodiment,the circulation supply 145 includes a heat sink. In another embodiment,the circulation supply 145 includes a heat source. In one embodiment, atemperature of the pedestal 110 is maintained between about −20° C. andabout 1000° C.

A first RF power generator 122 having a frequency below the VHF range orbelow the HF range (e.g., in the MF or LF range, e.g., between about 100kHz and about 60 MHz, such as about 2 MHz) is coupled to the electrode108 through an impedance match circuit 124 via an RF feed conductor 123.A second RF power generator 120 having a frequency in the MF or LF rangemay also be coupled to the electrode 108 through the impedance matchcircuit 124 via the RF feed conductor 123. In one embodiment, the firstRF power generator 122 has a frequency of about 2 MHZ and the second RFpower generator 120 has a frequency of about 60 MHz. In one embodiment,the impedance match circuit 124 is adapted to match an impedance of aplasma formed in the process volume 101 at the different frequencies ofthe RF power generators 120 and 122, as well as filtering to isolate thepower generators from one another. Output power levels of the RF powergenerators 120, 122 are independently controlled by a controller 126. Aswill be described in detail below, power from the RF power generators120, 122 is coupled to the electrode 108.

In one embodiment, the ceiling 106 is electrically conductive and is inelectrical contact with the electrode 108. Power from the impedancematch circuit 124 is conducted through the ceiling 106 to the electrode108, for example, through the shafts 188, 190 or other conductor. In oneembodiment, the chamber body 102 is maintained at ground potential. Inone embodiment, grounded internal surfaces (i.e. chamber body 102)inside the chamber 100 are coated with a process compatible materialsuch as silicon, carbon, silicon carbon materials, or silicon-oxidematerials. In an alternative embodiment, grounded internal surfacesinside the chamber 100 are coated with a material such as aluminumoxide, yttrium oxide, or zirconium oxide.

With the two RF power generators 120, 122, radial plasma uniformity inthe process volume 101 can be controlled by selecting a distance betweenthe electrode 108 and pedestal 110. In this embodiment, the RF powergenerators 120, 122 produces an edge-high radial distribution of plasmaion density in the process volume 101 and a center-high radialdistribution of plasma ion density. With such a selection, the powerlevels of the two RF power generators 120, 122 are capable of generatinga plasma with a substantially uniform radial plasma ion density.

As shown, a cable passage 192 is formed at least partially through theelectrode 108 and normal to a bottom surface 199 of the electrode 108.The RF feed conductor 123 and other cables or conductors are disposedthrough the cable passage 192. A cable insulator 170 in the cablepassage 192 if configured to prevent capacitive coupling of the RF feedconductor 123 to a cooling plate 175. In one embodiment, the cableinsulator 170 is fabricated from a dielectric material. The coolingplate 175 includes a material suitable for transferring thermal energy,such as metallic materials, for example aluminum or stainless steel.

In one embodiment, the electrode 108 includes an electrode plate 150. AD.C. blocking capacitor 156 is connected in series with the output ofthe impedance match circuit 124. In one embodiment, the RF feedconductor 123 is directly coupled to the electrode plate 150 through theceiling 106 and the cable passage 192. In this embodiment, a portion ofthe RF feed conductor 123 which is disposed in the process volume 101 isflexible in nature to accommodate movement of the electrode 108. In oneembodiment, the RF feed conductor 123 from the impedance match circuit124 is connected to the ceiling 106 rather than being directly connectedto the electrode 108. In such an embodiment, RF power from the RF feedconductor 123 is capacitively coupled from the ceiling 106 to theelectrode 108.

In one embodiment, the electrode 108 includes an insulating plate 174formed from an electrically insulating material and coupled to aninsulator pipe 176. The insulator pipe 176 may be formed of the same orsimilar material as the insulating plate 174. The insulating plate 174and the insulator pipe 176 electrically isolate and prevent capacitivecoupling between the electrode plate 150 and the ceiling 106.

In one embodiment, the electrode 108 includes a silicon plate 158disposed on the electrode plate 150. The silicon plate 158 is positionedby and held adjacent to the electrode plate 150 via an insulator clamp172. The insulator clamp 172 is fabricated from an electricallyinsulating material, such as quartz or aluminum oxide. The silicon plate158 functions to protect a surface 199 of the silicon plate 158 fromcorrosive species which are generated in the process volume 101 duringprocessing of the substrate 111 or cleaning of the chamber body 102.

In one embodiment, internal passages 178 for conducting a thermallyconductive liquid and/or gas inside the cooling plate 175 are connectedto a thermal media circulation supply 180. The thermal media circulationsupply 180 may also function as a heat sink or a heat source. In oneembodiment, the electrode 108 is encased, at least partially, in aprotective member 182. The protective member 182 surrounds the electrode108 such that the surface 199 of the silicon plate 158 is exposed withinthe process volume 101 and other surfaces of the electrode 108 arecovered by the protective member 182. In one embodiment, the protectivemember 182 is formed from an electrically insulating material, such asquartz or polytetrafluoroethylene. In one embodiment, a groundingmaterial, such as aluminum or the like, is disposed on the protectivemember 182 when the protective member 182 is formed from an electricallyinsulating material. In another embodiment, the protective member 182 isfabricated from a metallic material, such as aluminum or stainlesssteel. The protective member 182 functions to protect various surfacesof the electrode 108 from corrosive species which are generated in theprocess volume 101 during processing of the substrate 111 or cleaning ofthe chamber body 102. In the illustrated embodiment, the joints 187, 189are coupled to the protective member 182, however, it is contemplatedthat the joints 187, 189 may be coupled to other regions of theelectrode 108 depending upon the desired implementation.

In one embodiment, upper gas injectors 130 provide process gas into theprocess volume 101 through a first valve 132. Lower gas injectors 134provide process gas into the process volume 101 through a second valve136. The upper gas injectors 130 and the lower gas injectors 134 aredisposed in sidewalls of the chamber body 102. Gas is supplied from aplurality of process gas supplies 138 through a plurality of valves 140which may include the first and second valves 132 and 136. In oneembodiment, the selection of gas species and the rates at which gas isdelivered into the process volume 101 are independently controllable.For example, the type and/or rate of gas flowing through the upper gasinjectors 130 may be different from the type and/or rate of gas flowingthrough the lower gas injectors 134. The controller 126 controls thestate of the valves 140.

In one embodiment, an inert gas, such as argon or helium, is suppliedinto the process volume 101 through the upper gas injectors 130 and aprocess gas is supplied into the process volume 101 through the lowergas injectors 134. In this embodiment, the inert gas delivered to theprocess volume 101 adjacent the electrode 108 functions to buffer theelectrode 108 from a reactive plasma formed in the process volume 101,thus increasing the useful life of the electrode 108. In anotherembodiment, process gas is supplied to the process volume 101 throughboth the upper gas injectors 130 and the lower gas injectors 134.

In one embodiment, plasma is generated in the process volume 101 byvarious bulk and surface processes, for example, by capacitive coupling.In one embodiment, plasma generation is also facilitated by energeticion bombardment of the surface 199 of the top electron-emittingelectrode 108. In one example, the electrode 108 is biased with asubstantially negative charge, such as by application of voltage formthe voltage supply 154. In one embodiment, bias power applied to theelectrode 108 is between about 1 KW and about 10 KW with a frequency ofbetween about 400 kHz and about 200 MHz. It is believed that ionsgenerated by a capacitively coupled plasma are influenced by an electricfield that encourages bombardment of the electrode 108 by the ionsgenerated from the plasma.

The ion bombardment energy of the electrode 108 and the plasma densityare functions of both RF power generators 120 and 122. The ionbombardment energy of the electrode 108 is substantially controlled bythe lower frequency power from the RF power generator 122 and the plasmadensity in the process volume 101 is substantially controlled (enhanced)by the VHF power from the RF power generator 120. It is believed thation bombardment of the electrode 108 heats the electrode 108 and causesthe electrode 108 to emit secondary electrons. Energetic secondaryelectrons, which have a negative charge, are emitted from the surface199 of the electrode 108 and accelerated away from the electrode 108 dueto the negative bias of the electrode 108.

The flux of energetic electrons from the surface 199 of the electrode108 is believed to be an electron beam, and may be orientedsubstantially perpendicular to the interior surface of the electrode108. A beam energy of the electron beam is approximately equal to theion bombardment energy of the electrode 108, which typically can rangefrom about 10 eV to 5000 eV. In one embodiment, the plasma potential isgreater than the potential of the electrode 108 and the energeticsecondary electrons emitted from the electrode 108 are furtheraccelerated by a sheath voltage of the plasma as the secondary electronstraverse through the plasma.

At least a portion of the electron beam, comprised of the secondaryelectron flux emitted from electrode 108 due to energetic ionbombardment of the electrode surface 199, propagates through the processvolume 101 and reacts with process gases near the substrate 111. Withutilization of suitable process gases, such as chlorine containingmaterials, fluorine containing materials, bromine containing materials,oxygen containing materials, and the like, the electron beam inducesetching reactions on the substrate 111. It is believed that the electronbeams, in addition to the capacitively generated plasma, generatechemically reactive radicals and ions which adsorb to the surface of thesubstrate and form a chemically reactive polymer layer on the surface ofthe substrate 111.

In one embodiment, an RF bias power generator 162 is coupled through animpedance match 164 to the conductive mesh 144 or other electrode of thepedestal 110. In a further embodiment, a waveform tailoring processor147 may be connected between the output of the impedance match 164 andthe conductive mesh 144. The waveform tailoring processor 147 changesthe waveform produced by the RF bias power generator 162 to a desiredwaveform. The ion energy of plasma near the substrate 111 is controlledby the waveform tailoring processor 147. In one embodiment, the waveformtailoring processor 147 produces a waveform in which the amplitude isheld during a certain portion of each RF cycle at a level correspondingto a desired ion energy level. The controller 126 controls the waveformtailoring processor 147.

Accordingly, the electron beam induces chemical reactions to liberategas phase volatile products and etch the substrate 111. Etching of thesubstrate 111 is also influenced by other factors, such as pressure. Inone embodiment, a vacuum maintained in the process volume 101 duringelectron beam etching of the substrate 111 is between about 0.1 Torr andabout 10 Torr. The vacuum is generated by a vacuum pump 168 which is influid communication with the process volume 101. The pressure within theprocess volume 101 is regulated by a throttle valve 166 which isdisposed between the process volume 101 and the vacuum pump 168.

Other factors which influence etching characteristics of the substrate111 include the angle ⊖ at which the surface 199 of the electrode 108 isdisposed relative to the substantially horizontal orientation of thesurface 110 a of pedestal 110 and the substrate 111 disposed thereon. Inone embodiment, the angle ⊖ is between about 1° and about 45°, such asbetween about 5° and about 30°, for example, between about 10° and about20°. As a result of the tilting of the electrode 108 to an orientationthat is non-parallel to the ceiling 106 and surface 110 a of thepedestal 110, secondary electrons contact the substrate 111 atsubstantially non-perpendicular angles which enable the substrate 111 tobe etched with slanted features. Slanted etching is believed to enableadvanced feature formation and can advantageously be implemented in theformation of various optical devices and the like.

FIG. 2 schematically illustrates another embodiment of the EBRPEapparatus 100. In the illustrated embodiment, the electrode 108 and theceiling 106 are maintained in a parallel and substantially horizontalposition. The support surface 110 a of the pedestal 110 is capable ofbeing positioned in a non-horizontal orientation relative to asubstantially horizontal orientation of the electrode 108. In otherwords, the pedestal 110 is movable such that the surface 110 a of thepedestal 110 can be positioned in a non-parallel orientation relative tothe surface 199 of the electrode 108. Aspects of the embodimentillustrated in FIG. 2 which are common to the embodiment of FIG. 1 aredescribed above.

The ceiling 106 is coupled to and supports the electrode 108 within theprocess volume 101. In one embodiment, the electrode 108 is coupled bymechanical clamping to the ceiling 106 such that the surface 199 of theelectrode 108 is exposed to the process volume 101 and faces the supportsurface 110 a of the pedestal 110. In this embodiment, the ceiling 106is a support for the electrode 108 which includes an insulating layer150 containing a conductive mesh 152 facing the surface 199. A D.C.blocking capacitor 156 is connected in series with the output of theimpedance match circuit 124. In one embodiment, the RF feed conductor123 form the impedance match circuit is connected to the conductive mesh152. In another embodiment, the RF feed conductor 123 from the impedancematch circuit 124 is connected to the electrode support or ceiling 106rather than being directly connected to the electrode 108. In such anembodiment, RF power from the RF feed conductor 123 is capacitivelycoupled from the electrode support to the electrode 108.

In one embodiment, internal passages 178 for conducting a thermallyconductive liquid and/or gas inside the ceiling 106 are connected to athermal media circulation supply 180. The thermal media circulationsupply 180 acts as a heat sink or a heat source. The mechanical contactbetween the electrode 108 and the ceiling 106 is sufficient to maintainhigh thermal conductance between the electrode 108 and the ceiling 106.

The pedestal 110 is coupled to a support shaft 212 by a joint 210. Thejoint 210 rotatably couples the pedestal to the support shaft 212 toenable movement of the pedestal 110 between one or more angles G. Thejoint 210 is disposed between the base layer 146 of the pedestal 110 anda topmost portion of the support shaft 212. Examples of suitable jointtypes for the joint 210 include ball and socket joints, pivot joints,hinge joints, saddle joints, universal joints, and the like. A topmostportion of the support shaft 212 has a tapered surface 214. The taperedsurface 214 extends from the joint 210 with an increasing radius downthe support shaft 212. As such, a radius of the support shaft 212 at thejoint 210 is less than the radius of the support shaft 212 elsewherealong a length of the support shaft 212. Thus, the tapered surface 214enables the pedestal 110 to be positioned at various angle magnitudeswithout interference from the support shaft 212. It is also contemplatedthat conduits extending from one or more of the voltage supply 148, theimpedance match 164, and the circulation supply 145 extend through thesupport shaft 212 and the joint 210 to the pedestal 110.

In one embodiment, a plurality of actuators 202, 204 are coupled to thechamber body 102 in the process volume 101. In another embodiment, theplurality of actuators 202, 204 are disposed outside of the processvolume 101. The actuators 202, 204 which may be electrical, pneumatic,mechanical, and/or hydraulic in nature of actuation, are coupled toshafts 206, 208 which extend from respective actuators 202, 204 to thepedestal 110. In one embodiment, the actuators 202, 204 are linearmotors or stepper motors. In one embodiment, the shafts 206, 208 areleads screws or ball screws. In embodiments where the actuators 202, 204are disposed outside of the process volume 101, the shafts 206, 208 areconfigured to extend from the actuators 202, 204 through the chamberbody 102 to the pedestal 110. In this embodiment, sealing apparatus maybe disposed at regions of the chamber body 102 where the shafts 206, 208extend through the chamber body 102.

In one embodiment, the shaft 206 is disposed between the actuator 202and the pedestal 110 and movably actuates the pedestal 110 about thesupport shaft 212. Similarly, the shaft 208 is disposed between theactuator 204 and the pedestal and movably actuates the pedestal 110about the support shaft 212. The shafts 206, 208 may be telescopic toenable different magnitudes of travel to facilitate an angledpositioning of the pedestal. For example, as illustrated in FIG. 2 , theshaft 206 is extended to a greater degree than the shaft 208 to orientthe surface 110 a of the pedestal 110 at a non-zero angle relative tothe surface 199 of the electrode 108 within the process volume 101.

Each of the shafts 206, 208 is coupled to the pedestal 110 by arespective joint 218, 216. For example, the shaft 206 is coupled to thepedestal 110 by the joint 218 and the shaft 208 is coupled to thepedestal 110 by the joint 216. The joints 216, 218 are rotational typejoints that allow the pedestal 110 to move independently of the shafts206, 208. Examples of suitable joint types for the joints 216, 218include ball and socket joints, pivot joints, hinge joints, saddlejoints, universal joints, and the like.

The ability to angle the surface 110 a of the pedestal 110 with respectto the surface 199 of the electrode 108 provides for the ability toperform slanted etching on the substrate 111. The angle ⊖ at which thesurface 110 a of the pedestal 110 is disposed relative to thesubstantially horizontal orientation of the surface 199 of the electrode108 influences etching characteristics of the substrate 111, among otherfactors. In one embodiment, the angle ⊖ is between about 1° and about45°, such as between about 5° and about 30°, for example, between about10° and about 20°. As a result of the angled disposition of the pedestal110, secondary electrons contact the substrate 111 at substantiallynon-perpendicular angles which enable the substrate 111 to be etchedwith slanted features. Slanted etching is believed to enable advancedfeature formation and can advantageously be implemented in the formationof various optical devices and the like.

In operation, the pedestal 110 is positioned in a substantiallyhorizontal orientation during placement of the substrate 111 on thepedestal 110. After the substrate 111 is secured to the pedestal 110,the surface 110 a of the pedestal 110 is tilted to the desired angle ⊖by extension of the shafts 206, 208 by the actuators 202, 204. An EBRPEprocess is performed while the pedestal 110 is in the tilted orientationand the pedestal 110 is returned to a substantially horizontalorientation after EBRPE processing has stopped.

FIG. 3 illustrates an actuator assembly 316 of the EBRPE apparatus 100according to an embodiment described herein. The actuator assembly 316is configured to extend or retract either of the shafts 188, 190 intothe process volume 101. The actuator assembly 316 includes a shaft 304,a link 310, and a motor 308. The motor 308 is disposed on a motor baseplate 318 and supported by the link 310. A power supply 320 supplieselectrical power to the motor 318.

A brace 302 is coupled to the chamber body 102 and supports the actuatorassembly 316. A first end of the shaft 304 is coupled to the brace 302via a connector 306. A second end of the shaft 304 opposite the firstend is coupled to the chamber body 102 via the connector 306. The link310 is moveably coupled to the shaft 304. For example, the shaft 304 andlink 310 may comprise a ball screw and ball nut, respectively.

The link 310 is configured to transfer linear or rotational energy fromthe motor 308 to the shaft 304. In one embodiment, the shaft 304 isstationary and the motor 308 is configured to move the link 310 alongthe shaft 304. In another embodiment, the motor 308 may be disposed onthe brace 302 and configured to move the shaft 304 with a link 310 thatis fixably coupled to the motor base plate 318.

The actuator assembly 316 is fluidly sealed from the process volume 101by bellows 312 and an seal 314. The shaft 190 moveably couples theelectrode 108 to the motor base plate 318. FIG. 3 depicts a portion ofthe chamber body 102 and the electrode 108. While a single actuatorassembly 316 is shown in FIG. 3 , it is contemplated that one or moreadditional actuator assemblies may couple the electrode 108 to thechamber body 102.

By utilizing electron beams generated in accordance with the embodimentsdescribed above, reactive species which are not readily obtained withconventional etching processes may be generated. For example, reactivespecies with high ionization and/or excitation/dissociation energies maybe obtained with the EBRPE methods and apparatus described herein. It isalso believed that the EBRPE methods described herein provide foretching rates equivalent to or greater than conventional etchingprocesses, but with improved material selectivity.

For example, EBRPE methods are believed to provide improved etchselectivity due to the separation of threshold electron beam energiesused to induce etching reactions. For example, with certain polymerizinggas chemistries, the threshold energy utilized to etch silicon oxidematerials is much greater than the threshold energy utilized to etchsilicon. As a result, it is possible to achieve etch selectivities ofabout 5:1 or greater. In one embodiment, EBRPE is believed to enableabout 5:1 silicon:silicon oxide etch selectivity. In another embodiment,EBRPE is believed to enable about 5:1 tungsten:silicon nitride etchselectivity.

The kinetic energy of electrons is also much less than that of ions. Asa result, substrate damage is reduced because the potential forsputtering is reduced. Moreover, by controlling the electron beamenergy, such as by application of RF power to the electrode, EBRPE isbelieved to provide a “softer” etch than conventional etching processes.With improved control, EBRPE is able to produce tapered etch profiles,such as etching profiles utilized in certain shallow trench isolationapplications. Moreover, by enabling slant etching by either tiltpositioning of the electrode or the pedestal, advanced etching profilesand operations may be performed.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A substrate processing apparatus, comprising: achamber body defining a volume; a pedestal disposed in the volume; aceiling coupled to the chamber body opposite the pedestal; and anelectrode disposed in the volume between the pedestal and the ceiling,wherein the electrode is movable to orient a surface of the electrodefacing a surface of the pedestal in a non-parallel orientation.
 2. Theapparatus of claim 1, wherein a plurality of actuators are disposed inthe ceiling and operable to control an angular orientation of theelectrode.
 3. The apparatus of claim 2, wherein a plurality of shaftscouple the electrode to the plurality of actuators.
 4. The apparatus ofclaim 3, wherein the plurality of shafts are coupled to the electrode bya plurality of joints.
 5. The apparatus of claim 3, wherein theelectrode includes a cable passage surrounded by a cable insulator. 6.The apparatus of claim 1, wherein the surface of the electrode facingthe pedestal is coupled to a plate.
 7. The apparatus of claim 6, whereinthe plate comprises a silicon containing material.
 8. The apparatus ofclaim 7, wherein the electrode is surrounded by a protective member suchthat the plate is exposed to the volume.
 9. The apparatus of claim 8,wherein protective member comprises aluminum.
 10. The apparatus of claim1, further comprising: a first gas injector fluidly coupled to thevolume through the chamber body adjacent the electrode; and a second gasinjector fluidly coupled to the volume through the chamber body adjacentthe pedestal.
 11. A substrate processing apparatus, comprising: achamber body defining a process volume; a pedestal disposed in theprocess volume configured to support a substrate; a ceiling coupled tothe chamber body opposite the pedestal; and an electrode disposed in theprocess volume between the pedestal and the ceiling, wherein theelectrode is movable to orient a surface of the electrode facing asurface of the pedestal in a non-parallel orientation; and a controllerconfigured to perform a method for electron beam reactive plasmaetching, the method comprising: delivering a process gas to the processvolume; applying low frequency RF power to the electrode disposed in theprocess volume opposite the pedestal upon which a substrate ispositioned; energizing the process gas to form a plasma in the processvolume; accelerating ions from the plasma toward the electrode;generating an electron beam from electrons emitted from the electrode;and etching the substrate using an electron beam generated fromelectrons emitted from the electrode.
 12. The substrate processingapparatus of claim 11, wherein the low frequency RF power has afrequency of about 2 MHz.
 13. The substrate processing apparatus ofclaim 11, wherein the electrode is formed from one or more of siliconcontaining materials, carbon containing materials, silicon-carboncontaining materials, or silicon-oxide containing materials.
 14. Thesubstrate processing apparatus of claim 11, wherein the electrode isformed from a metal oxide containing material or one or more of siliconcontaining materials, carbon containing materials, silicon-carboncontaining materials, or silicon-oxide containing materials.
 15. Thesubstrate processing apparatus of claim 11, wherein the electrode isformed from a metal oxide containing material.
 16. The substrateprocessing apparatus of claim 15, wherein the metal oxide containingmaterial is selected from the group consisting of aluminum oxide,yttrium oxide, and zirconium oxide.
 17. The substrate processingapparatus of claim 11, wherein the plasma is generated by capacitivecoupling.
 18. The substrate processing apparatus of claim 11, whereinthe process gas includes one or more of chlorine containing materials,fluorine containing materials, bromine containing materials, or oxygencontaining materials.
 19. The substrate processing apparatus of claim11, wherein the electron beam has a beam energy between about 10 eV to20,000 eV.
 20. A substrate processing apparatus, comprising: a chamberbody defining a process volume; a ceiling coupled to the chamber body;an electrode, disposed in the process volume and coupled to the ceiling,for performing electron beam reactive plasma etching; a pedestal,disposed in the process volume opposite the electrode, coupled to asupport shaft, one or more shafts coupled to the electrode to orient theelectrode in a non-parallel manner relative to the ceiling; one or moreball screw actuators coupled to the one or more shafts, to extend orretract the one or more shafts within the process volume; a first gasinjector couple to the chamber body adjacent the electrode; and a secondgas injector coupled to the chamber body adjacent the pedestal.